A block brake actuator, normally a so called brake unit containing a brake cylinder and a stack adjuster can conventionally be provided with a brake block holder suspended therefrom. The suspension by hangers or suspension links is such that the brake block holder (provided with brake blocks) can pivot in the plane of the actuator push rod to and fro braking engagement with a wheel to be braked.
When the brake actuator is fixedly mounted in the vicinity of the wheel to be braked, only very limited axial movements of the wheel or wheel-set can be allowed.
In recent years there has been a clear tendency towards rail vehicle designs allowing greater axial movements of the wheel-sets. One way of solving the problem of using a conventional brake unit of the kind described at axially movable wheels is shown in the International P.C.T. Publication No. WO-A-80/00682, published Apr. 17, 1980, where the whole unit together with the suspension and brake block holder is laterally movably suspended.
For different reasons such a solution may not be utilized in many cases, and preferably the actuator is to be fixedly mounted in a rail vehicle underframe or bogie in the vicinity of the wheel to be braked.
The problem of braking an axially movable wheel by means of a fixedly mounted brake actuator may as known be solved in that the brake block holder is laterally movably suspended relative to the brake actuator. As shown in U.S. Pat. No. 4,406,444 the hangers suspending the brake block holder can consist of leaf springs.